Habitat

East Indian hygrophila inhabits shallow water bodies and wetlands including ponds, streams, and marshes. It is found both in shallow water bodies (<3m depth) and on the banks of deeper water bodies, where it is not fully submerged. It exhibits the most growth in temperatures between 18-30C but can survive in near freezing conditions. It additionally can survive in low light conditions, and low CO2 levels, as it can pull CO2 from the atmosphere when not submerged.

Life Cycle

East Indian hygrophila reproduces asexually. Reproduction occurs through a process of fragmentation in August, after the growing season is completed. The shoot of the plant, up to the root crown, breaks off. In large populations, these shoots go to the surface and create floating mats. The plants flower between September and November. Slowly, portions of the shoot float downstream, and root upon making contact with soil. These shoots overwinter and begin Spring growth in March. They grow throughout the spring and summer, reaching the water’s surface and emerging, before again fragmenting in August.

Ecological Threat

East Indian hygrophila has low light requirements yet still displays rapid growth, so it is a strong competitor compared to native submerged vegetation. It can displace native vegetation, resulting in a monoculture, which reduces aquatic animal habitat and food availability. East Indian hygrophila also impacts agricultural systems and recreation. It has been known to colonize and clog irrigation pipes, as well as disturb boating and swimming activities.